Embodiments of the present disclosure generally relate to drivers, and especially to drivers having high efficiency in a wide input range and comprising back-end stage buck circuits, and especially to LED lamps comprising the drivers.
In the LED constant current driving power supply, a two-stage driving circuit is a common technical solution. The two-stage driving circuit comprises a front-end circuit and a back-end circuit, wherein the front-end circuit is configured for power factor correction and constant voltage output control, and the back-end circuit is configured for constant-current output control. The buck circuit is a preferred solution for the back-end circuit. In practical applications, the user's requirements for the efficiency of the LED driver circuit will never stop. In order to adapt to a variety of application occasions, the LED driver circuit is required to have high efficiency not only in full load, but also in light load.
However, when the two-stage driving circuit comprising a buck back-end circuit is in full load, i.e., when an output voltage of the buck circuit is close to an input voltage of the buck circuit, the efficiency of the buck circuit is high. However, when the driving circuit is in light load, i.e., when the output voltage of the buck circuit is much lower than the input voltage of the buck circuit, the efficiency of the buck circuit is low, thereby limiting the efficiency of the driving circuit as a whole.
Therefore, it is desirable to provide a method to solve at least one of the problems described above.